AMPHIOXUS
lancelet, amphioxus
(noun) small translucent lancet-shaped burrowing marine animal; primitive forerunner of the vertebrates
Source: WordNet® 3.1
Noun
amphioxus (plural amphioxi or amphioxuses)
The lancelet, particularly of the genus Branchiostoma.
Source: Wiktionary
Am`phi*ox"us, n. Etym: [NL., fr. Gr. (Zoöl.)
Definition: A fishlike creature (Amphioxus lanceolatus), two or three
inches long, found in temperature seas; -- also called the lancelet.
Its body is pointed at both ends. It is the lowest and most
generalized of the vertebrates, having neither brain, skull,
vertebræ, nor red blood. It forms the type of the group Acrania,
Leptocardia, etc.
Source: Webster’s Unabridged Dictionary 1913 Edition